Skip to main content

Gearing Up for the Gigabit Era

Following years of primping and preening, DOCSIS 3.1 is almost ready for its closeup.

In sync with field testing now underway and limited deployments slated for later this year, CableLabs is expected to soon start official certification and qualification testing on network and home-side equipment based on DOCSIS 3.1, a platform that is built to deliver speeds of up to 10 Gigabits per second downstream and at least 1 Gbps upstream.

DOCSIS 3.1 will be used to bring widespread access to Gigabit speeds on the industry’s hybrid fiber-coax networks, with an early emphasis on the downstream path. Among the technology’s early champions are operators such as Comcast, which is already testing DOCSIS 3.1-based downstream traffic in the field, and Liberty Global.

Indicating that cable is inching closer to bringing DOCSIS 3.1 to the masses, the industry last month launched a website dedicated to “Gigasphere,” the consumer-facing brand for DOCSIS 3.1 that was introduced last April at the Cable Show in Los Angeles by the National Cable & Telecommunications Association, in collaboration with the Cable & Telecommunications Association for Marketing, CableLabs and Cable Europe.

The new site, launched ahead of this week’s INTX conference (the rechristened Cable Show) in Chicago, provides consumers with high-level details about the platform and how it will be used to support bandwidth-intensive apps and service such as 4K/ Ultra HD video, the “smart home” and the associated so-called Internet of Things.

While operators have been using DOCSIS 3.0 to offer cable-modem speeds that provide advertised downstream speeds of 250 Mbps and (in extreme cases) as much as 500 Mbps, DOCSIS 3.1 will help them more efficiently pursue a “billboard” speed in the 1-Gbps range.

“DOCSIS 3.1 is critical to delivering 1-Gig speeds and over,” Todd Kessler, senior vice president of product management at Arris, said. “There’s a lot of pressure on us and the industry to get this to a deployment-ready stage.”

State-of-the-art DOCSIS 3.0 equipment, which can bond up to 32 downstream channels, can hit maximum speeds of 1 Gbps, but not nearly as efficiently as DOCSIS 3.1 can.


CableLabs’s next D3.1 interop is scheduled to run from April 27 through May 9, which means it will overlap a bit with this week’s INTX event. But that work is expected to get products several steps closer to a Cable Labs-certified state.

The reason why the current interop is so lengthy is to give CableLabs time to iron out issues between vendors and to run through Acceptance Test Plans, or ATPs, which are automated tests designed to ensure that devices are adhering to the specifications ahead of official testing later this year.

CableLabs is also working to prep vendors for coming field trials to work out operational issues and make software changes, ensuring they will be ready to scale up deployments with operators once products pass certification/qualification testing.

“We’re working iteratively to make sure they [the vendors] can get to a good end state as quickly as possible,” Dan Rice, senior vice president of network technology at CableLabs, said.

Under the current DOCSIS certification testing schedule, there are only two opportunities left in 2015: certification wave 115, this summer, and wave 116, slated for this fall.

While DOCSIS 3.1 cable modems will need to meet all of the spec’s requirements, CableLabs is expected to offer more wiggle room to network-side cable-modem termination systems (CMTSs), which are easier to tweak and modify than modems once they are deployed.

With that in mind, CableLabs is expected to use the kind of “feature- set testing” for DOCSIS 3.1 CMTSs it has been employing for DOCSIS 3.0 CMTSs. Under that approach, vendors can focus on and test against a core set of DOCSIS 3.1 functions, and then test separately as other elements, such as upstream channel bonding, are added to the product roadmap.

On the CMTS end, Arris’s DOCSIS 3.1 strategy is focusing on the E6000, a high-density chassis that is evolving in to a full-fledged Converged Cable Access Platform (CCAP) that will also integrate video functions.

That product, which has been shipping for about a year and a half, will be software-upgradeable to D3.1 on the downstream end, Kessler said.

At the SCTE Cable-Tec Expo last fall, Arris showed DOCSIS 3.1-modulated traffic working at the physical layer with prototype silicon from two cable-modem chipmakers — Intel and STMicroelectronics. Arris is also doing some work with Broadcom, which announced a DOCSIS 3.1-based modem reference design, the BCM93390, in January at International CES in Las Vegas.

Arris, Kessler said, will develop upstream and downstream capabilities for D3.1, but expects to focus more initially on the downstream. “We expect to be ready for the initial deployments by the end of the year for DOCSIS 3.1,” he said. “This will be a big year for achievements and milestones.”

Cisco Systems achieved a milestone of its own late last month, delivering a “live ping” of DOCSIS 3.1-based downstream traffic in the lab, meaning those packets successfully completed a round trip through the system, according to John Chapman, a Cisco fellow and chief technology officer of the company’s Cable Access unit.

It marked a significant move for the company’s new flagship CCAP, the cBR-8, which is now shipping. The cBR-8, code-named “Battlestar,” is heading out the door with DOCSIS 3.0 on board, but is designed to be field-upgradable to D3.1 via new line cards, Chapman said, hopeful that Cisco will start to ship D3.1 CCAPs with upstream capabilities by the first half of 2016.

“It’s our job is to make sure that DOCSIS is competitive to fiber,” Chapman said, noting that D3.1 will likely be viewed as a technology that is best suited from a cost and performance perspective to “brownfields,” while fiber likely presents a more attractive approach for MSOs in new, “greenfield” scenarios.

On the cable-modem side, D3.1 has already attracted support from at least three chipmakers — Broadcom, Intel and STMicroelectronics.

MaxLinear has been working closely with Intel, providing a single-chip front-end tuner that can support both DOCSIS 3.1 and DOCSIS 3.0 traffic. The aim is to be ready to support full commercial launches of DOCSIS 3.1 by the first quarter of 2015.

“This is a major gateway upgrade,” Jim Koutras, director of product marketing at MaxLinear, said.


While it’s necessary to have the equipment for DOCSIS 3.1 deployments, getting engineers and field technicians trained for the new platform will also be vital.

As part of its work with Cable- Labs, the Society of Cable Telecommunications Engineers (SCTE) has already developed DOCSIS 3.1 coursework and training materials, offering a one-day on-site course as well as a self-paced online version.

The four-module course, for mid- to senior-level data and headed techs, covers the gamut, including the fundamental nuts and bolts of the platform, details on the modifications that are being made to the DOCSIS network’s physical and media-access control layers and operations- based elements such as network maintenance and security.

SCTE is seeing a relatively even split between those requesting on-site and self-paced courses on DOCSIS 3.1, with training already extended to “several large operators” and some vendors, senior director of advanced technologies Steve Harris said. “There are a lot of new tools involved.”

DOCSIS 3.1 at a Glance

A snapshot of what’s going inside cable’s next-gen IP platform for HFC:

• Eschewing the use of 6MHz- and 8MHz-wide channels utilized by today’s DOCSIS networks, DOCSIS 3.1 will rely on blocks of orthogonal frequency division multiplexing (OFDM) subcarriers.

• When combined with Low Density Parity-Check, a forward-error correction scheme that uses less bandwidth than the current Reed-Solomon approach, DOCSIS 3.1 is expected to be about 50% more efficient from a bits-per-hertz perspective than DOCSIS 3.0.

• Modems: The first wave of D3.1 customer-premises equipment will be hybrids that support DOCSIS 3.0 traffic and a fresh swath of DOCSIS 3.1-based spectrum. The DOCSIS 3.0 side will support a minimum of 24 bonded downstream and eight upstream single-carrier QAM channels (D3.0’s state-of-the-art is 32-by-8), while the D3.1 end calls for a minimum configuration of two 192-MHzwide OFDM blocks in the downstream, and two 96 MHz-wide OFDM blocks in the upstream.

• The first generation of hybrid D3.1 modems will aim to support 5 Gbps down by 1 Gbps up when fully loaded. A next-generation version could shoot for downstream speeds of 10 Gbps-plus.